Pixhawk bootloader

i am using pixhawk 2.4.8, i had flashed arduplane firmware version 4.0.9 via mission planner, two weeks ago and was working fine till now, suddenly when i powered it its showing I/O bootloader error , and the main LED is not glowing, i tried reinstalling the firmware but still it is giving the same error. kindly guide me as to what should i do

ArduPilot assistance is best sought via discuss.Ardupilot.org
First thing to try is forcing an IO update by holding the safety switch in whilst powering up the board. If that doesn’t fix it, I’d suggest you visit the ArduPilot forum.